Sawdust burner



J. PUDNEY sAwnusT BURNER Sept. 7, 1937.

Filed May 4, 195e tij;

Patented Sept. 7, 1937 UNITED STATES SAWDUST BURNER y i .I ames StuartPudney, Victoria, British Columbia, Canada Application May 4, 1936,Serial No. 77,841

In Canada December 2, 1935 Claims.

This invention relates to an improved sawdust burner.

' An object of the present invention is the provision of a sawdustburner in the form of a complete unit which may be applied to heatingdevices of all types, particularly ranges, domestic and industrialfurnaces and Dutch ovens.

` Another object is the provision of a sawdust burner of greatlyincreased efiiciency in which substantially complete combustion isensured by supplying preheated air to the products of combustion in asecondary combustion chamber.

A further object is the provision of a sawdust burner which will keepthe smoke pipe and flue clear of soot by complete combustion of thefuel, thus eliminating` the re hazard created by clogged pipes becomingoverheated.

In the known types of burners the fuel is burned and the products ofcombustion drawn off through the smoke pipe. In this way gases and sootcontaining relatively great heat value pass out through the flue and arelost. Not only does this reduce the efciency of the fuel but the sootsettles on the walls of the smoke pipe and flue making frequent cleaningnecessary in order to prevent the pipes from becoming overheated. Thisinvention overcomes these objectionable features by providing a sawdustburner having a primary combustion chamber in which the fuel in burned.The products of combustion then pass into a secondary combustion chamberin which they are mixed with preheated air and completely burned. Thepreheated air breaks up the productsof combustion and mixes them withoxygen to form a highly combustible gas which is ignited by the heatfrom the primary combustion chamber.

'I'he present invention consists essentially of primary combustionchamber containing a grate and a hopper adapted to supply fuel to thegrate, said chamber communicating with a secondary combustion chamberwithin the heating device to which the sawdust burner is applied, andmeans for supplying preheated air to the secondary combustion chamber asmore fully described in the following specification and illustrated inthe accompanying drawing, in which:-

Fig. 1 is a vertical section through a sawdust burner and the range towhich it is applied, only a part of the latter being shown, and

Fig. 2V is a plan view of the sawdust burner with the hopper removed andhaving certain parts broken away for the sake of clarity.

Referring more particularly to the drawing, A is the sawdust burnerapplied to an ordinary range (Cl. 126-222) i B.` The-burner A comprisesa hollow base I0 adapted to form a water reservoir I I. A housing I2,removably secured to the base I0 in a any suitable mannen formstherewith a primary combustion chamber i3. The base I0 has a raisedsection 5 I4 forming a slope I5 in the chamber I3.

A shoulder l5 surrounds an opening Il in the top of the housing I2 andplates I3 having slots I 3 are secured to the sides of shoulder. Ahopper 23 `having a hinged cover 2| is formed at its lower l0 end with areduced opening 22 and at each side thereof with flanges 23 adapted toride in the slots I9. A plate 24'removably mounted on one end cf'theshoulder I5 has its upper surface in line with 'the bottoms of the slotsI9 so that the hop- 15 per may be slid along the slots onto the platewhen it is desired to gain access to the primary cornbustion chamberfrom above. The plate 24 -may be vremoved from the shoulder when it isnot needed.

A sloping chute or plate 25 mounted on the inner side of the top ofhousing I2 extends beneath the opening II and has itslower end suspendedabove a grate 25 situated in the chamber I3. The inner end of the grate26 isvlower than the 25 outer end lying beneath the plate 25 and abutsagainst the slope I 5; The outer end of the chamber I3 is provided witha door 28 having a damper 29 through which' air may pass into saidchamber. The side walls of the chamber are'lined with 30 fire brick 30.7

Theraised sectionV I4 of the hollow base Il) is provided with a tube 3|which extends through the base upwardly and terminates in an opening 32in the top of the housing I2. A member 33, 35 'which may be cylindricalor any other desired shape, is mounted at its lower end in the opening32, said member extends upwardly into the range B through a heatingcompartment 34 .in said range and passes through a partition 35. rIhis40 partition 35 takes the place of the usual grate of the range B andthe member 33 is sealed therein so that no air may pass from thecompartment 34 between said member and the partition into the upper partof the range. 'I'he member 33 45 forms a secondary combustion chamber 36and has a plurality of rows of holes 3l. A pipe 38 mounted in the upperend of the tube 3| extends upwardly into and centrally of the chamber 36and terminates just below the level of the parti- 50 tion 35. A cap 39is fitted onto the upper end of the pipe 38 and has a plurality of holes40. The tube 3|, pipe 38 and holes 4|] form a passageway lIIcommunicating at the lower end with the at mosphere outside the sawdustburner and at the 55 upper end with the interior of the secondary com.-bustion chamber 36.

Air enters the compartment 34 through the usual damper 42 of the rangeB. Water enters the reservoir Il through an inlet pipe 43 and passestherefrom through an outlet pipe 44 which extends through the chamber 36and out through one of the walls of the range.

In operation, sawdust flows from the hopper through the opening 22, overthe plate onto the grate 25 in the primary combustion chamber I3 whereit is burned. Air entering the chamber through the damper 29 passesthrough the grate and sawdust to aid combustion. The products ofcombustion from this fire pass along the chamber I3 and up into thesecondary combustion chamber 36. Air entering the passageway 4| isheated as it flows through the pipe 38 and passes out in jets throughthe holes 40 into the secondary combustion chamber where it mixes withthe products of combustion. At the same time air flowing through thedamper 42 is preheated in compartment 34 and is injected in jets throughthe holes 3l also to mix with the products of combustion in thesecondary combustion chamber. These two streams of preheated air breakup the products of combustion` and add oxygen thereto to form a highlycombustible gas which ignites from the heat generated in the primarycombustion chamber.

This burning of the products of combustion from the primary chamber notonly completes the combustion of the fuel to give substantially 100%efficiency but it eliminates soot so that nothing but a useless gaspasses on through the range and flue.

Water circulating in the reservoir Il is heated by the re in the primarychamber and is further heated by the fire in the secondary chamber as itflows through the outlet pipe 44.

While this device has been described as a sawdust burner, it is to beunderstood that coal or any suitable other fuel could be used withoutaltering the construction of the device.

From the above it will readily be seen that a sawdust burner has beenprovided in which substantially complete combustion is ensured thusgreatly increasing its efliciency and in which the soot is completelyburned thus eliminating clogged pipes and fiues.

What I claim as my invention is:

1. A sawdust burner adapted to be applied to a heating device comprisinga primary combustion chamber, means for supplying fuel to a grate insaid chamber, a secondary combustion chamber associated with the primarychamber and extending into the heating device and means for supplyingpreheated air from the heating device and the atmosphere outside theheating device to the secondary chamber where it is mixed with theproducts of combustion from the primary chamber to ensure completecombustion thereof.

2. A sawdust burner adapted to be applied to a heating device comprisinga primary combustion chamber, means for supplying fuel to a grate insaid chamber, a secondary combustion chamber connected to the primarychamber and extending into the heating device, means extending centrallyof the secondary chamber for supplying preheated air thereto and meansfor supplying preheated air to said secondary chamber through the wallsthereof, said preheated air being mixed with the products of combustionfrom the primary chamber to ensure complete combustion thereof.

3. A sawdust burner adapted to be applied to a heating device comprisinga primary combustion chamber, a hopper for supplying fuel to a grate insaid chamber, a secondary combustion chamber connected to the primarychamber and extending into the heating device, a heating compartmentsurrounding the secondary chamber, means for supplying preheated airfrom said compartment to the secondary chamber and means communicatingwith the atmosphere outside the burner and the interior of the secondarychamber for supplying additional preheated air thereto, said preheatedair being mixed in the secondary chamber with the products of combustionfrom the primary chamber to ensure complete combustion thereof.

4. A device according to claim 3 in which the wall of the secondarycombustion chamber is provided with a plurality of rows of holes throughwhich preheated air is injected in jets from the compartment into thesecondary chamber and in which the means for supplying additionalpreheated air to the secondary chamber comprises a passagewaycommunicating with the atmosphere outside the burner and extendingupwardly centrally of the secondary chamber and terminating adjacent thetop thereof.

5. A sawdust burner adapted to be applied to a heating device comprisinga primary combustion chamber having a hollow base with a housing securedthereto, means for circulating water through said hollow base, saidhousing having an opening in its top, a shoulder surrounding theopening, plates secured to each side of the shoulder each having a slottherein, a hopper slidably mounted in said slots and a plate removablymounted on one end of the shoulder having its upper surface in line withthe bottoms of the slots whereby said hopper may be slid onto the platein order to gain access to the primary chamber from above.

JAMES STUART PUDNEY.

